Wet spinning apparatus



April 2, 1957 w. R. SCHMITZ WET SPINNING APPARATUS Filed Dec. 24. 1953 Wm4 TM m m w M m 1 w M a ATTORNEY United States Patent G WET SPINNINGAPPARATUS William R. Schmitz, Larchmont, N. Y.

Application December 24, 1953, Serial No. 400,317

3 Claims. (Cl. 18-8) This invention relates to apparatus for treatingfibers, yarns, threads, filaments and the like and more particularly itrelates to apparatus for treating synthetic fibers in which there is aconcurrent flow of the liquid bath as the fibers are passed through it.

In the spinning of rayon yarns, for example, a viscose spinning solutionis extruded through minute orifices of a spinnerette into a coagulatingor solidifying liquid bath. Thereby, a parallel series of continuousfilaments are formed, which are subsequently converged into a tow andwithdrawn from the bath after being suliiciently hardened. In the priorspinning apparatus, the stagnant liquid bath causes considerable drag onthe moving filaments and in order not to break or over stretch them, thedraw-off speed must be kept relatively low. Also to reduce friction, thedistance the filaments are moved through the bath must be shortened. Asa result a lower quality yarn is produced at a slower rate, than wouldotherwise be possible if the drag on the filaments were eliminated.

To overcome these difiiculties pumps and similar devices have beenutilized to induce a concurrent fiow of the bath in the same directionas the moving filaments. However this practice has been foundunsatisfactory for several reasons. For example, it requires theaddition of numerous mechanical parts to the spinning machine, which inturn substantially increases the cost of construction. Also, it isdifiicult and sometimes impossible to synchronize the speed of flow ofthe spinning bath with the speed of the thread. Furthermore, it greatlycomplicates the stringing up procedure.

Accordingly, it is an object of this invention to provide a simplifiedand inexpensive structure for treating fibers, threads, and the likewherein the drag on the fibers, as they are moved through a liquid bath,is substantially reduced.

Another object of this invention is to provide a structure of the abovecharacter which permits the filament to move a considerable distancethrough a treating bath without appreciably increasing frictional drag.

Another object of this invention is to provide a structure of the abovecharacter in which the speed of flow of the liquid bath is readilyadjusted with respect to the speed of the moving filament.

These and other objects of this invention are attained by providing abaffie within the receptacle containing the coagulating bath andadjacent the path of the filaments, whereby the motion of the filamentsinduces a circulatory flow of the bath about the bafile. As a result,the direction and speed of the induced flow of the liquid bath issubstantially the same as the direction of movement and the velocity ofthe filament, and thus the friction therebetween is substantiallyreduced.

For a better understanding of the present invention reference may be hadto the accompanying drawings in which:

Fig. l is a schematic view in longitudinal section of a rayon spinningdevice constructed in accordance with the 'ice invention, showing thedisposition of the baflle within the liquid bath.

Fig. 2 is a view in transverse section taken along line 22 of Fig. 1,looking in direction of the arrows.

With reference to Figures 1 and 2, a spinning machine schematicallyshown therein, includes a tank 10 having a bottom wall 11 and side walls12 and 13, containing an acid spinning bath 14. An inlet chamber 15(enclosed by an inclined partition 18 and the bottom 11 and side wall13) communicates with. the interior of the tank through an inlet port 19formed between a horizontally disposed end portion 20 of the partition10 and the bottom tank wall 11. During the spinning operation, the bath14 may be constantly replenished by maintaining a slightly greaterhydrostatic pressure within the inlet chamber 15, than in the tank.

A bracket 21 mounted on the tank Wall 13, has a plate 22 formed integraltherewith and inclined towards the opposite tank wall 12. As is bestshown in Figure 2, the plate 22 carries a convergence guide 25comprising a plate member 26 formed with a V shaped notch 27. The plate22 also is formed with an inclined shelf 28 which extends downwardly andterminates adjacent the bottom 11 of thetank.

The tank 10 is formed with a separate spinning trough 30 by verticalpartitions 31 and 32, which are secured to opposite sides 33 and 34 ofthe convergence guide support plate 22, and extend towards the left handtank wall 12. The lower edges 35 of the partitions 31 and 32 are alsosecured to the inclined partition 18. A baffle 38 is mounted between thepartitions 31 and 32, and is disposed in a parallel plane with respectto the shelf 28, forming therebetween a passageway 39. The upper orright hand end of the bafile 38 is spaced from the convergence guideplate 22, thereby forming opening 40 which communicates with passageway39.

it will be understood that the tank 10 may be divided into a pluralityof similar individual spinning troughs by mounting additional verticalpartitions and baffles in the manner described above.

A goose neck 44 is pivotally connected at one end to the left-hand tankwall 12 by means of an apron block 45. The opposite end of the gooseneck 44 extends into the bath 14, and is provided with a cylindricallyshaped spinnerette 46. In the viscose spinning process subsequently tobe described, a viscose solution is extruded through minute orifices inthe spinnerette 46, into the acid spinning bath 14. As the extrudedsolution comes in contact with the bath, it is solidified and hardened,thereby forming a series of filaments (a strand) indicated at 47.

Thereafter, thestrand 47 is combined into a rope or tow 48, as it isdrawn through the V-shaped notch 27 in the convergence guide 25. The tow48 is then directed under a hold-down type guide 49 and a stripper guide50, to a direction-changing roller 51 which is mounted on the right-handtank wall 13. It will be noted that the tow 48 does not emerge from thebath 14 until it passes between the guides 49 and 50. Also it will beseen in Figure 1, that the strand 47 moves in a plane generally parallelto the baflle 38.

As the strand 47 is moved towards the convergence guide 25, its movementis utilized to induce a concurrent, circulatory flow of the bath 14,about the bafiie 38, as indicated by the arrows. Thus, a few momentsafter the spinning operation is commenced, the induced flow of the bathincreases to a point where it nearly equals the speed and direction ofthe moving strand 47, and as a result the friction created therebetweenis substantially reduced. Also in this connection, it will be seen thatthe direction of flow of the bath 14 through the inlet port 19, asindicated by the arrows, is approximately the same as the induced flowabout the baffle 38, and this may be utilized to increase the velocityof the latter and afford more uniform mixing of the incoming solutionwith the treating solution.

To better understand the important advantages of this invention, it willbe appreciated that the best quality yarn is produced under conditionswhere the filament at the time of formation is relatively weak, thefilament is immersed in the bath for a relatively long period of time,and where the filament is not subjected to an undue amount of stretchingbefore it has been thoroughly solidified by the acid bath. To furtherclarify the firstmentioned condition, there is an optimum acid bathconcentration which will produce a final filament of maximum strength,however, it is characteristic that at this optimum acid bathconcentration the strength of the newly formed filament is relativelyweak. Although higher acid concentrations will cause the initiallyformed filament to be stronger, the ultimate filament is unfortunatelyweaker. In the prior spinning devices these optimum conditions cannot beattained because the friction created by moving the filaments through astagnant bath causes excessive stretching of the filaments. As a result,the outer surfaces of the filaments become highly oriented before theircores are susceptible to orientation. Thereafter, when the cores becomesolidified and are then oriented by further stretching, the outersurfaces of the filaments are ruptured. The filaments formed in thismanner have a low tenacity in comparison with filaments in which thecores and outer surfaces are stretched and oriented, simultaneously.

By utilizing spinning apparatus of the type described above, it will beappreciated that it is possible to spin rayon filaments at a greaterrate of speed, and to move them a greater distance through the bathwithout materially increasing the frictional drag. Also, an initiallyweaker filament acid spinning solution may be used because the filamentsremain in contact therewith, for a longer period of time. As a result,it is possible to produce better quality yarn at a greater rate ofspeed. Furthermore, this new spinning apparatus makes it possible tospin rayon yarn under conditions where the fila ments coagulate soslowly, or are so weak in the region of formation, that spinning in astagnant bath would be impossible at any commercial speed.

It is to be understood that the form of the invention described above issusceptible to considerable modification, and may be used in conjunctionwith other types of filament-treating apparatus. Accordingly,- the formof the invention disclosed herein should be considered as illustrativeand not as limiting the scope of the following claims.

I claim:

' 1. In an apparatus for treating filaments in a fluid bath, areceptacle for a coagulating fluid bath, means including a spinneretdisposed within said receptacle for continuously extruding viscosefilaments into the bath, guide means disposed above and at a distancefrom the spinneret forguiding the filaments through said receptacle inan upwardly inclined path, an upwardly inclined bafile mounted withinthe receptacle below the path of travel of the filaments through thereceptacle, the upper end of said bafile being submerged below the upperlevel of the bath, the movement of the filaments through the bathinducing an upward flow of said fluid above the battle, means forming adownwardly sloped surface beneath and spaced apart from the underside ofsaid baflle, said underside of said bafile and said downwardly slopedsurface forming a passage therebetween for the return flow of saidfluid, and means forming a guiding surface extending upwardly from thedownwardly sloped surface, but spaced apart from the upper end of thebattle, for deflecting the fluid around the upper end of the baflle andinto the return passage beneath the baffle, whereby a continuous flow ofthe fluid is maintained around said balfle.

2. An apparatus as set forth in claim 1 including an inlet port disposedbeneath the lower end of the down wardly sloped surface to replenish thefluid in the receptacle and to feed said fluid approximately in thedirection of the return flow of the fluid toward the base of the baflie.

3, In an apparatus for treating filaments in a fluid bath, a receptaclefor a coagulating fluid bath, means including a spinneret disposedwithin said receptacle for continuously extruding viscose filaments intothe bath, guide means disposed above and at a distance from thespinneret V for guiding the filaments through said receptacle in anupwardly inclined path, a pair of upright walls spaced apart within thereceptacle, thereby forming a channel through which the filaments areguided in their passage through the receptacle, an upwardly inclinedbaflle plate mounted between the pair of upright walls and below thepath of travel of the filaments through the receptacle, the upper end ofsaid baffle plate being submerged below the upper level of the bath,whereby the passage of the filaments through said channel induces anupward flow of said fluid through said channel and above the baffleplate, means intermediate said pair of upright walls forming adownwardly sloped surface beneath and spaced apart from andsubstantially parallel to said baflle plate, said baffle plate and saiddownwardly sloped surface forming a passage therebetween for the returnflow of said fluid in a direction opposite to the flow of the fluidabove the bafiie plate, and means extending upwardly from the downwardlysloped surface forming a guide surface for deflecting the fluid aroundthe upper end of the bafile plate and into the return passage, whereby acontinuous flow of the fluid is maintained around said bafile plate.

References Cited in the file of this patent UNITED STATES PATENTS2,659,102 Rarick Nov. 17, 1953

